functional

<?php
$start = microtime(true);
$i=0;
$stack = [];
while ($i!=1000){
    array_push($stack,1);
    $i++;
}
$time_elapsed_secs = microtime(true) - $start;
echo $time_elapsed_secs;

spl

<?php
$start = microtime(true);
$i=0;
$stack = new SplStack();
while ($i!=1000){
    $stack->push('1');
    $i++;
}
$time_elapsed_secs = microtime(true) - $start;
echo $time_elapsed_secs;